Throughout this application various publications are referenced. The disclosures of each of these publications in their entireties are hereby incorporated by reference in this application.
The reversible phosphorylation of proteins on serine and threonine residues is a major intracellular control mechanism. Cell proliferation, cell signaling, gene expression and mitosis are among the cellular functions regulated by this mechanism. The phosphorylation state of a protein is controlled by kinases, which phosphorylate proteins, and phosphatases, which dephosphorylate proteins. A number of families and types of protein phosphatases exist, including tyrosine phosphatases and serine/threonine protein phosphatases (PPs). An increase in expression of certain PPs has been described in several tumor types. Modulation of expression of one or more serine/threonine protein phosphatases is desired for research, diagnostic, and therapeutic uses.
Small molecule inhibitors of protein phosphatases have been used to study PP function. The best characterized of these is okadaic acid, which is the causative agent of diarrhetic shellfish poisoning. It is a potent inhibitor of PP2A and PP1 and a much (roughly a thousandfold) less potent inhibitor of PP2B. In spite of this difference in sensitivity, okadaic acid cannot easily be used to discriminate between PP1 and PP2A in cells. Other inhibitors of one or more PPs include tautomycin, cyclosporin A, dinophysistoxin, calyculin, microcystin, nodularin and cantharidin. Cairns et al., 1994, J. Biol. Chem. 269:9176-9183; Wera and Hemmings, 1995, Biochem. J. 311:17-29.
Improved inhibitors of protein phosphatases are desired for therapeutic, diagnostic and research uses. Specific inhibitors of particular PP isoforms are particularly desired.
Oligonucleotides have been employed as therapeutic moieties in the treatment of disease states in animals and man. For example, workers in the field have now identified antisense, triplex and other oligonucleotide compositions which are capable of modulating expression of genes implicated in viral, fungal and metabolic diseases.
Antisense oligonucleotides have been safely administered to humans and clinical trials of several antisense oligonucleotide drugs, targeted both to viral and cellular gene products, are presently underway. For example, the oligonucleotide drug fomivirsen (ISIS 2922), has been shown to be effective against cytomegalovirus retinitis in AIDS patients, and is presently in Phase III clinical trials. BioWorld Today, Apr. 29, 1994, p 3. Another oligonucleotide drug, ISIS 2302, has been shown to be effective in Crohn's disease, a form of inflammatory bowel disease. In a placebo-controlled Phase II trial of ISIS 2302 in Crohn's disease, a statistically significant (p=0.0001) corticosteroid-sparing effect was achieved while inducing durable remissions in almost half of the drug-treated patients (versus 0% in the placebo group). The mean duration of remission in the responding patients was prolonged, lasting almost five months following a single course of treatment. In addition, ISIS 2302 was shown to be safe and well-tolerated. Canadian Digestive Diseases Week conference in Quebec City, Quebec, Canada.
It is thus established that oligonucleotides can be useful therapeutic instrumentalities and can be useful in treatment of cells and animal subjects, especially humans.